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	$214.65	7.295%	$230.3087	$230.31	$230.30	$230.30
Purchase #2	$121.46	7.497%	$130.5659	$130.57	$130.55	$130.60
Purchase #3	$174.54	12.436%	$196.2458	$196.25	$196.25	$196.20
Purchase #4	$211.65	13.275%	$239.7465	$239.75	$239.75	$239.70
Purchase #5	$178.48	3.719%	$185.1177	$185.12	$185.10	$185.10
Purchase #6	$55.31	11.612%	$61.7326	$61.73	$61.75	$61.70
Purchase #7	$134.45	6.186%	$142.7671	$142.77	$142.75	$142.80
7 purchase totals =	$1,090.54		$1,186.4843	$1,186.50	$1,186.45	$1,186.40