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	$184.30	6.673%	$196.5983	$196.60	$196.60	$196.60
Purchase #2	$12.42	5.555%	$13.1099	$13.11	$13.10	$13.10
Purchase #3	$236.83	11.513%	$264.0962	$264.10	$264.10	$264.10
Purchase #4	$117.56	9.700%	$128.9633	$128.96	$128.95	$129.00
Purchase #5	$74.39	3.287%	$76.8352	$76.84	$76.85	$76.80
Purchase #6	$196.60	8.487%	$213.2854	$213.29	$213.30	$213.30
Purchase #7	$201.58	8.352%	$218.416	$218.42	$218.40	$218.40
7 purchase totals =	$1,023.68		$1,111.3043	$1,111.32	$1,111.30	$1,111.30