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	$101.69	10.852%	$112.7254	$112.73	$112.75	$112.70
Purchase #2	$59.43	5.861%	$62.9132	$62.91	$62.90	$62.90
Purchase #3	$59.98	3.204%	$61.9018	$61.90	$61.90	$61.90
Purchase #4	$83.58	11.455%	$93.1541	$93.15	$93.15	$93.20
Purchase #5	$194.33	11.269%	$216.229	$216.23	$216.25	$216.20
Purchase #6	$236.27	5.533%	$249.3428	$249.34	$249.35	$249.30
Purchase #7	$120.69	5.487%	$127.3123	$127.31	$127.30	$127.30
7 purchase totals =	$855.97		$923.5786	$923.57	$923.60	$923.50