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	$88.65	4.488%	$92.6286	$92.63	$92.65	$92.60
Purchase #2	$27.45	4.334%	$28.6397	$28.64	$28.65	$28.60
Purchase #3	$99.86	8.484%	$108.3321	$108.33	$108.35	$108.30
Purchase #4	$233.94	6.638%	$249.4689	$249.47	$249.45	$249.50
Purchase #5	$37.43	13.619%	$42.5276	$42.53	$42.55	$42.50
Purchase #6	$238.41	7.223%	$255.6304	$255.63	$255.65	$255.60
Purchase #7	$106.88	9.734%	$117.2837	$117.28	$117.30	$117.30
7 purchase totals =	$832.62		$894.5110	$894.51	$894.60	$894.40