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	$174.63	11.159%	$194.117	$194.12	$194.10	$194.10
Purchase #2	$55.59	8.859%	$60.5147	$60.51	$60.50	$60.50
Purchase #3	$96.64	5.837%	$102.2809	$102.28	$102.30	$102.30
Purchase #4	$154.43	10.800%	$171.1084	$171.11	$171.10	$171.10
Purchase #5	$64.83	9.740%	$71.1444	$71.14	$71.15	$71.10
Purchase #6	$36.27	11.643%	$40.4929	$40.49	$40.50	$40.50
Purchase #7	$244.46	13.120%	$276.5332	$276.53	$276.55	$276.50
7 purchase totals =	$826.85		$916.1915	$916.18	$916.20	$916.10