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	$165.69	10.372%	$182.8754	$182.88	$182.90	$182.90
Purchase #2	$241.69	6.849%	$258.2433	$258.24	$258.25	$258.20
Purchase #3	$65.26	3.788%	$67.732	$67.73	$67.75	$67.70
Purchase #4	$209.49	5.637%	$221.299	$221.30	$221.30	$221.30
Purchase #5	$99.86	9.541%	$109.3876	$109.39	$109.40	$109.40
Purchase #6	$148.68	8.217%	$160.897	$160.90	$160.90	$160.90
Purchase #7	$147.89	13.300%	$167.5594	$167.56	$167.55	$167.60
7 purchase totals =	$1,078.56		$1,167.9937	$1,168.00	$1,168.05	$1,168.00