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	$179.28	9.526%	$196.3582	$196.36	$196.35	$196.40
Purchase #2	$64.35	11.250%	$71.5894	$71.59	$71.60	$71.60
Purchase #3	$155.59	6.656%	$165.9461	$165.95	$165.95	$165.90
Purchase #4	$249.99	5.454%	$263.6245	$263.62	$263.60	$263.60
Purchase #5	$90.65	10.633%	$100.2888	$100.29	$100.30	$100.30
Purchase #6	$84.68	5.488%	$89.3272	$89.33	$89.35	$89.30
Purchase #7	$196.31	4.633%	$205.405	$205.41	$205.40	$205.40
7 purchase totals =	$1,020.85		$1,092.5392	$1,092.55	$1,092.55	$1,092.50