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	$149.87	10.614%	$165.7772	$165.78	$165.80	$165.80
Purchase #2	$7.26	4.206%	$7.5654	$7.57	$7.55	$7.60
Purchase #3	$28.53	13.796%	$32.466	$32.47	$32.45	$32.50
Purchase #4	$236.49	13.680%	$268.8418	$268.84	$268.85	$268.80
Purchase #5	$165.90	11.328%	$184.6932	$184.69	$184.70	$184.70
Purchase #6	$209.48	8.619%	$227.5351	$227.54	$227.55	$227.50
Purchase #7	$150.72	13.619%	$171.2466	$171.25	$171.25	$171.20
7 purchase totals =	$948.25		$1,058.1253	$1,058.14	$1,058.15	$1,058.10