Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$95.36	6.263%	$101.3324	$101.33	$101.35	$101.30
Purchase #2	$115.85	6.233%	$123.0709	$123.07	$123.05	$123.10
Purchase #3	$167.80	7.444%	$180.291	$180.29	$180.30	$180.30
Purchase #4	$165.31	11.740%	$184.7174	$184.72	$184.70	$184.70
Purchase #5	$154.73	6.609%	$164.9561	$164.96	$164.95	$165.00
Purchase #6	$206.82	12.776%	$233.2433	$233.24	$233.25	$233.20
Purchase #7	$196.59	10.592%	$217.4128	$217.41	$217.40	$217.40
7 purchase totals =	$1,102.46		$1,205.0239	$1,205.02	$1,205.00	$1,205.00