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	$184.73	5.543%	$194.9696	$194.97	$194.95	$195.00
Purchase #2	$30.44	4.444%	$31.7928	$31.79	$31.80	$31.80
Purchase #3	$55.87	4.778%	$58.5395	$58.54	$58.55	$58.50
Purchase #4	$180.87	13.353%	$205.0216	$205.02	$205.00	$205.00
Purchase #5	$72.54	8.798%	$78.9221	$78.92	$78.90	$78.90
Purchase #6	$12.28	13.108%	$13.8897	$13.89	$13.90	$13.90
Purchase #7	$74.88	3.865%	$77.7741	$77.77	$77.75	$77.80
7 purchase totals =	$611.61		$660.9094	$660.90	$660.85	$660.90