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	$194.37	3.272%	$200.7298	$200.73	$200.75	$200.70
Purchase #2	$33.70	12.357%	$37.8643	$37.86	$37.85	$37.90
Purchase #3	$194.66	8.867%	$211.9205	$211.92	$211.90	$211.90
Purchase #4	$120.47	8.182%	$130.3269	$130.33	$130.35	$130.30
Purchase #5	$152.25	8.786%	$165.6267	$165.63	$165.65	$165.60
Purchase #6	$245.46	12.565%	$276.302	$276.30	$276.30	$276.30
Purchase #7	$76.70	13.166%	$86.7983	$86.80	$86.80	$86.80
7 purchase totals =	$1,017.61		$1,109.5685	$1,109.57	$1,109.60	$1,109.50