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	$94.76	4.840%	$99.3464	$99.35	$99.35	$99.30
Purchase #2	$183.99	6.685%	$196.2897	$196.29	$196.30	$196.30
Purchase #3	$67.86	8.341%	$73.5202	$73.52	$73.50	$73.50
Purchase #4	$161.89	4.816%	$169.6866	$169.69	$169.70	$169.70
Purchase #5	$141.74	9.498%	$155.2025	$155.20	$155.20	$155.20
Purchase #6	$189.59	3.741%	$196.6826	$196.68	$196.70	$196.70
Purchase #7	$193.80	8.695%	$210.6509	$210.65	$210.65	$210.70
7 purchase totals =	$1,033.63		$1,101.3789	$1,101.38	$1,101.40	$1,101.40