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	$196.85	8.159%	$212.911	$212.91	$212.90	$212.90
Purchase #2	$69.88	4.370%	$72.9338	$72.93	$72.95	$72.90
Purchase #3	$188.89	7.280%	$202.6412	$202.64	$202.65	$202.60
Purchase #4	$83.48	8.705%	$90.7469	$90.75	$90.75	$90.70
Purchase #5	$177.89	13.632%	$202.14	$202.14	$202.15	$202.10
Purchase #6	$37.44	12.243%	$42.0238	$42.02	$42.00	$42.00
Purchase #7	$238.29	4.463%	$248.9249	$248.92	$248.90	$248.90
7 purchase totals =	$992.72		$1,072.3216	$1,072.31	$1,072.30	$1,072.10