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	$98.54	5.305%	$103.7675	$103.77	$103.75	$103.80
Purchase #2	$10.38	8.818%	$11.2953	$11.30	$11.30	$11.30
Purchase #3	$82.97	9.864%	$91.1542	$91.15	$91.15	$91.20
Purchase #4	$233.57	3.173%	$240.9812	$240.98	$241.00	$241.00
Purchase #5	$243.94	9.766%	$267.7632	$267.76	$267.75	$267.80
Purchase #6	$196.40	13.303%	$222.5271	$222.53	$222.55	$222.50
Purchase #7	$103.50	4.217%	$107.8646	$107.86	$107.85	$107.90
7 purchase totals =	$969.30		$1,045.3531	$1,045.35	$1,045.35	$1,045.50