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	$197.37	11.446%	$219.961	$219.96	$219.95	$220.00
Purchase #2	$84.72	7.445%	$91.0274	$91.03	$91.05	$91.00
Purchase #3	$93.58	12.608%	$105.3786	$105.38	$105.40	$105.40
Purchase #4	$192.92	5.238%	$203.0251	$203.03	$203.05	$203.00
Purchase #5	$55.74	7.435%	$59.8843	$59.88	$59.90	$59.90
Purchase #6	$244.44	11.290%	$272.0373	$272.04	$272.05	$272.00
Purchase #7	$90.34	12.788%	$101.8927	$101.89	$101.90	$101.90
7 purchase totals =	$959.11		$1,053.2064	$1,053.21	$1,053.30	$1,053.20